Ex parte Baurin: OTDP after Allergan

What did the Appeals Review Panel actually decide?

In Ex parte Baurin, issued on 18 December 2025, the USPTO Appeals Review Panel acted on sua sponte rehearing to reverse a PTAB decision that had itself reversed an examiner’s obviousness-type double patenting (OTDP) rejections, and reinstated the examiner’s rejections of the claims at issue.

The procedural posture is worth pausing on, because it is unusual and it tells you how seriously the Office takes the question. An examiner rejected claims on OTDP. The Board reversed the examiner. The Appeals Review Panel then took the case up on its own motion and reversed the Board’s rehearing decision, putting the rejections back in place. The panel comprised USPTO Director John A. Squires, PTAB Chief Judge Kalyan Deshpande and PTAB Acting Deputy Chief Judge Michelle Ankenbrand — that is, the Director sitting with the Board’s leadership rather than a routine three-judge panel. The decision was designated as precedential.

The application in question is U.S. Application No. 17/135,529, directed to antibody-like binding proteins. The examiner relied on U.S. Patent No. 10,882,922 as the OTDP reference. For readers managing biologics and antibody families in the United States — where continuation practice is deep and family trees are long — this is squarely the fact pattern you already have on file.

Why does Allergan v MSN matter here?

Because Allergan USA, Inc. v. MSN Labs (Fed. Cir. 2024) is the decision many applicants have been treating as a safe harbour for exactly this situation, and Baurin tells you where the harbour ends.

In Allergan, the Federal Circuit held that a first-filed, first-issued, later-expiring claim cannot be invalidated by a later-filed, later-issued, earlier-expiring reference claim having a common priority date. That holding was widely read in prosecution as removing OTDP exposure across large continuation families sharing a priority date: if the patent under attack was the parent — first filed, first issued — a later child that happened to expire earlier could not be turned against it.

The important word in that holding is the sequence of conditions. Allergan is not a general statement that family members with a common priority date cannot be OTDP references. It is a conjunction of characteristics, and each element of the conjunction has to be present in the case in front of you.

Why did the Allergan exception not save the ’529 application?

Because the ARP concluded that the exception established in Allergan did not apply, on the basis that the ’529 application does not have the first actual filing in its family.

That is the operative finding, and it is narrow in the best sense: it turns on a fact about the file, not on a reformulation of doctrine. The applicant’s position depended on the application occupying the Allergan position — first filed, first issued, later expiring, common priority date. The ARP found the first limb missing. Once the application is not the first actual filing in its family, the Allergan conjunction is not satisfied and the exception is unavailable, whatever the expiry dates say.

For in-house counsel, the practical translation is uncomfortable but clear. “Common priority date” is not the test. “Earliest claimed priority” is not the same thing as “first actual filing”. A family built on a provisional, a PCT entry, a bypass continuation and a chain of continuations can very easily contain an application whose priority claim reaches the front of the family but whose actual filing does not. If your OTDP risk memo says “foreclosed by Allergan”, it needs to identify which member was actually filed first, and when.

What is the anti-harassment rationale doing in this decision?

It is doing independent work: the ARP concluded that the Board erred in dismissing the anti-harassment rationale as inadequate to support the examiner’s OTDP rejections.

This is the part of Baurin with the longest reach. OTDP is commonly discussed as though it were exclusively a patent term problem — a doctrine aimed at preventing unjustified extension of exclusivity beyond the statutory term. On that view, if no term extension is available on the facts, the rejection should fall away. The Board appeared to reason in that direction. The ARP held that dismissing the anti-harassment rationale was error.

The consequence for prosecution planning is that the absence of a term-extension benefit does not, by itself, dispose of an OTDP rejection at the Office. An examiner may invoke a rationale directed at the burden of multiple assertions rather than at term, and the Board may not treat that rationale as inadequate on its face. Strategies premised on “there is no term to gain here, so there is no OTDP problem” need re-testing.

Why does 1995 keep coming up in these cases?

Because the Uruguay Round Agreements Act took effect on 8 June 1995 and changed patent term from 17 years from issuance to 20 years from the earliest claimed priority date.

Under the pre-URAA regime, the term clock started at issuance, so the order in which family members issued largely determined the order in which they expired. Under the 20-years-from-earliest-priority measure, that alignment no longer holds: filing order, issue order and expiry order can come apart. That decoupling is what produces the Allergan fact pattern — a later-filed, later-issued patent that nonetheless expires earlier — and it is why a modern OTDP analysis requires three separate dates per family member, not one.

This is also where European-origin families are most exposed. A Paris Convention priority filing, a PCT, a national phase entry and a chain of continuations generate a set of dates that look tidy in a docketing system and messy in an OTDP analysis. The date your system displays as “priority” is not the date the ARP looked at in Baurin.

What does Baurin not settle?

It does not settle whether the anti-harassment rationale should be available at all where no term-extension concern is apparent — and the Office has said so itself.

The ARP stated that the Office would welcome clarification from the Federal Circuit if its precedents should not be read as permitting OTDP rejections based on the anti-harassment rationale where no term-extension concern is apparent. That is an invitation, and it should be read as one. The panel applied the reading it considered available to it while flagging, in terms, that the appellate court may see the matter differently. A precedential ARP decision that asks for appellate clarification is not a stable end point; it is a position pending review.

Two further limits follow from what the decision is. Baurin reversed the Board’s rehearing decision and reinstated an examiner’s rejections in a pending application. It is an outcome in examination. It does not, of itself, tell you how a district court or a post-grant tribunal would resolve an invalidity challenge on comparable facts, and readers should not budget on the assumption that it does. Nor does the decision alter the Allergan holding, which remains what the Federal Circuit said it is: a first-filed, first-issued, later-expiring claim cannot be invalidated by a later-filed, later-issued, earlier-expiring reference claim having a common priority date. Baurin addresses when an applicant is in that position, not what happens when it is.

Which pending families should you re-check now?

Any US continuation family where an OTDP rejection was assumed to be foreclosed by Allergan, and any family where the argument against OTDP rested on the absence of a term-extension benefit.

For the first group, the check is factual rather than legal: identify, for each family member, the actual filing date, the issue date and the expiry date, and confirm which member holds the first actual filing. If the application you are relying on is not that member, the Allergan exception was not available to it on the ARP’s reasoning in Baurin. For the second group, the check is one of exposure: an examiner may press a rationale that does not depend on term at all.

What should you do about it this quarter?

Run the file-date audit, re-open the memos that closed on Allergan, and plan for the cost of the alternatives rather than discovering it at final rejection.

Concretely: instruct US counsel to re-verify, family by family, whether the applications you care about are genuinely the first-filed and first-issued members with a common priority date, rather than accepting a docketing entry as the answer. Where they are not, budget for terminal disclaimers in the affected continuations and take the decision early, while it is still a prosecution choice rather than an appeal. Where your structure depends on assumptions about ownership across family members, put those assumptions in front of US counsel explicitly instead of carrying them forward from a pre-Baurin strategy note. And keep a watch item open on the Federal Circuit: the Office has asked for clarification, and the answer, whenever it comes, will change the calculation again.